CAMBRIDGE - Congressman Michael Capuano, a Democrat who is frequently named by political insiders as having high political aspirations, declined to rule out a run for the U.S. Senate should the opportunity present itself.

In an interview with PolitickerMA.com this week, Capuano, of Somerville, said he wouldn't rule out running but carefully qualified his answers by saying that he wasn't focused on the possibility.

"Who in their right mind would ever close the door on anything," Capuano said. "Anybody that tells you they have closed the door is either lying to you or lying to themselves. At the same time, that's not the same thing as saying I've got it all planned out, because anybody that's done that is crazy too. The answer is somewhere in the middle."

Capuano prefaced his answer by saying, "I don't do speculation," and said that he is focused on his job in Congress.

"I don't know about anybody else," he said when asked who else might be interested in running, "but for me, I really try to do everything I can to, number one, avoid answering these kinds of questions, and number two, to think about it too much."

Capuano is often mentioned as a possible Senate candidate should John Kerry join an Obama administration or if Edward Kennedy's health forced him to step down. Most recently, National Journal's Congress Daily reported that Capuano and Attorney General Martha Coakley, a Medford Democrat, may be best positioned for a run.

Capuano has more than $920,000 in his campaign war chest, a considerable amount, but less than fellow Congressmen Edward Markey ($2.7 million), Richard Neal ($2.18 million), John Tierney ($1.34 million), Stephen Lynch ($1.19 million) or Bill Delahunt ($1.12 million). Former Congressmen Martin Meehan and Joe Kennedy also have considerable campaign coffers, with $4.8 million and $1.87 million, according to Federal Election Commission Reports.

Nevertheless, Capuano also noted that he has both jumped at opportunities to run for higher office and declined them. He decided to run for Congress but declined to run for governor in 2006.

The Democrat also said that it is almost difficult to think about running for Senate since he still almost can't believe his career has followed the trajectory it has.

"I look at myself as I'm still that 16 year-old hanging out on the corner in Somerville," he said. "I know I'm not, but in my mind. And I wake up on a regular basis, particularly when I'm in Washington, I look up at that dome and, I'll be honest with you, I am waiting for someone to tap me on the shoulder and say, ‘we didn't mean you. You don't' belong here.' I've felt that way all my life about everything I've done."

Consequently, Capuano said it is hard for him to say for certain what he wants to do next. He also said, however, that he always looks to take advantage of opportunities.

"It really is difficult for me to ever say I have a plan," he said. "I don't have a plan. I never have. It is just kind of like, ‘Oh jeez, I've got this great opportunity, do I screw it up or do I make something out of it.'"

Note: This story comes from part of a lengthy interview with Congressman Capuano. Check out the first story, on whether state Sen. Dianne Wilkerson should resign, here. Stay tuned for more.